Hee Young Park fired a 10-under-par 61 on Saturday and moved ahead by a single stroke entering the final round of the Manulife Financial LPGA Classic.
Park, coming off a missed cut at the U.S. Women's Open, is 20-under-par 193 through 54 holes at Grey Silo Golf Course. She became the 11th player in LPGA Tour history to shoot 61.
"I didn't realize it," Park said, when asked if she was aware of how low she was going. "My long putting was pretty awesome. I just tried to trust it."
Angela Stanford remained in second place with a third-round 64. The five-time LPGA Tour winner is 19-under-par 194, one shot ahead of overnight leader Catriona Matthew, who shot 68 and dropped into third at 18-under.
"When you see everybody going low, you have to go with them or you're going to get left behind," said Stanford. "Any time the greens are soft, you can be more aggressive."
Meena Lee (65) is alone in fourth place at 17-under, while Anna Nordqvist (67) resides in fifth at 15-under.
Gerina Piller shot 62 and jumped into a tie for sixth at 14-under. She sits alongside Amy Yang (66) and Austin Ernst (67).
World No. 1 Inbee Park, the winner of the last three LPGA tournaments and the season's first three majors, shot 68. She is tied for ninth place with Suzann Pettersen (68) at minus-13.
"I had a lot of opportunities today but missed a lot of putts," Park said.
Stacy Lewis, ranked second in the world, shot 67 and moved into a tie for 12th at 11-under with three others.
Hee Young Park, who is seeking her second career LPGA Tour win, opened with a birdie before carding four straight pars. The 26-year-old highlighted her outward 32 with an eagle at the par-5 sixth and added a birdie at the eighth, but she truly impressed during her closing stretch.
Around the turn, she notched back-to-back birdies from the 10th to catch Matthew at 16-under, then added further gains at Nos. 13 and 15 to go in front.
Park birdied the 17th, then lipped out an eagle chip at the last, settling for birdie and a sparkling 61.
"It's going to be hard," Park said of closing out the win on Sunday. "I mean, everybody can hit it 10-under, 9-under any time, so I cannot breathe. I have to keep it going."
NOTES: Park's previous LPGA Tour win came at the 2011 CME Group Titleholders ... She is the 54-hole leader for just the second time in her six-year LPGA career. She last held the lead at the 2011 CME Group Titleholders ... Annika Sorenstam holds the 18-hole LPGA Tour record at 59.